This invention relates to lasers and more particularly to a soft x-ray laser.
Heretofore attempts have been made to produce x-ray amplification by an anisotropic spatial distribution in a plasma created by focusing a high-power laser beam in a line on a target. Because of the requirement for sufficiently high intensities at the target, the length of the focused line must be relatively short. It has been determined that plasmas generated in such a focused line are too short near the target to provide significant amplification. In addition, the plasmas are not uniform, they are not reproducible and they undergo interactions with nearby target material resulting in loss of gain. By the time such a line-plasma moves away from the target and has expanded freely in a relaxation mode to a dimension sufficiently large for formation of quasi-cw population inversions and significant gain, it generally becomes spatially isotropic and ionic densities drop to a level too low for useful application as a laser amplifier.
Since the advent lasers, researchers have developed many different types of lasers which are operable over a wide spectrum of different wavelengths. U.S. Pat. No. 3,882,312 is directed to a method of producing collimated x-radiation by suitably subjecting metallic ions to a pulse of laser energy from a conventional laser. This patent indicates that hard x-rays might have developed by irradiating anhydrous copper sulfate confined between two glass plates with a line-focused, Q-switched Nd: glass laser. X-radiation was assumed to be produced from copper ions formed during the laser excitation. However, it has been proven that the patented device does not lase.
The present invention has been set forth in an article, "An Extended Plasma Source for Soft X-ray Lasers" by J. F. Reintjes, R. H. Dixon and R. C. Elton, in Optics Letters, vol. 3, page 40, Aug. 1978 and is accordingly incorporated herein by reference.